Linda Schmid
Are you looking for greater energy efficiency in your new barndo? If you are, you are not alone. Energy efficiency translates to lower energy bills, greater comfort in your home, and the assurance that your home’s heating and cooling are more sustainable. For these reasons people are more conscious of energy efficiency than they used to be, and paying attention to your new home’s details can pay off in the long run. There are also tax credits under the Inflation Reduction Act (IRA) available for insulating homes and structures.
How is Energy Efficiency Attained in A Home?
One of the most basic ways that energy efficiency is built into a home is, of course, through insulation. A well-built and properly air-sealed, energy-efficient home will have insulation in the walls, ceilings, and foundation, and each of these parts of the structure can have different types of insulation. How do you know how effective the insulation will be? That can be determined based on R-value.
Of course, once you have determined what insulation will work well for you, don’t forget to take into account the quality and efficiency of windows, doors, ventilation, heating systems, and appliances. All these things and more will affect your home’s energy efficiency. Together these things are referred to as U-value. Be aware of air leakage; a leaky home can negate the energy efficiency of your home.
What is R-Value?
R-value is the rating given to a building component that represents its resistance to heat flowing through it. The higher the R-value, the greater the resistance. Greater resistance leads to greater energy efficiency, which can translate to lower energy bills and greater comfort in your home.
Some Basic Types of Insulation, Their Advantages, and Drawbacks:
- Batt: This is the traditional insulation that comes in a roll, often with a backing. There are many versions including fiberglass, cellulose, mineral wool, SPF, cotton or even wood fiber. All are fairly easy to install. Proper installation includes completely filling the cavity, cutting out around electrical boxes or other obstructions and splitting around wires or plumbing. Batt is often chosen for home insulation as it is affordable, and if faced it may not need a vapor barrier. Batts should not be compressed when installed as the insulation requires air space to work properly. Batt can leave nooks and crannies exposed, however, spray foam or caulk can properly air seal and insulate even small spaces. Care must be taken when handling the fiberglass version as it can irritate skin, eyes, and lungs.
- Cellulose: This is loose fill, usually made of recycled paper or fabric, and it can easily be used to fill in around pipes or just about anywhere you need it. However, breathing it in during installation can be dangerous due to the additives. Cellulose has a limited life span because some of these additives, such as flame retardants, can fade over time. Cellulose can begin to degrade from heat and moisture, the fill can begin to settle, and this insulation then needs to be replaced.
- Rigid Foam: This insulation comes formed like a board and is easy to install if you use the correct sealants, flashings, and tapes. It is long lasting since it does not settle or degrade like batt or cellulose. It is fire resistant and closed cell rigid foam is moisture resistant. Rigid foam can be used as continuous insulation, wrapping the frame in a protective barrier that combats thermal bridging. (Thermal bridging occurs when something conducts heat through the insulation. For example, wood framing can interrupt insulation and act as a conductor.) On the other hand, rigid foamcan be non-recyclable. It is also a less affordable form of insulation than some others.
- Spray Foam: Spray foam can offer great R-Values, but it can cost more than some other types of insulation. It comes in two forms: open cell and closed cell, which each have their own pros and cons. Open cell is especially great for filling cracks, crevices, and hard-to-reach spaces because it expands after it is sprayed. Open cell is not as impermeable as closed cell spray foam, however. Closed cell foam is so moisture resistant that no vapor barrier is required. However, a qualified installer is needed for both quality and safety. However, there are more natural polymer spray foams now that feature low-VOCs and are easier for the contractor to install.
Photos courtesy of Owens Corning
Commonly Used Insulation in a Post-Frame Barndo
Energy efficiency is one of the advantages that people often look for and find in a barndominium. According to Tim Noble of Kentuckiana Building Development LLC, barndos can be more efficient than traditionally built homes because of how they are framed.
Posts in a post-frame building are spaced further apart than studs in a stick-built (or traditionally built) home. Posts are often spaced 6 or 8 feet on center (6 or 8 feet from the center of one post to the center of the next). This creates a nice big space in which insulation has no interrupters or conductors allowing energy to penetrate the wall, which in turn saves on heating and cooling costs. Although nailing requirements for sheathing must be considered as they are typically far less than 6-8 feet apart.
“Walls are generally insulated with spray foam in a barndo,” Noble said. “Spray foam is popular because it has become more affordable and it allows no heat transfer between walls, sealing the space better than most forms of insulation.”
Josiah Loye COO of Country Carpenters, Inc. said that SIPs can also be used to insulate a barndo. SIPs are Structurally Insulated Panels. These panels are created by sandwiching a rigid foam core between two boards, such as OSB (oriented strand board). This can contribute to a very airtight and efficient wall.
The roof deck can be foam-sprayed also, depending on the build. If batt is used in the walls, builders will often blow insulation into the ceiling. If the design of the barndo leaves no space for blown-in insulation, rigid foam and/or a radiant barrier can be used in the roof. Attics can either be vented or unvented. Vented attics typically are insulated on the ceiling, most commonly with a loosefill insulation (fiberglass or cellulose). Cathedral ceilings that are vented can be insulated with either loosefill or batts. Unvented attics typically are done with spray foam but can also use rigid foam attached above or below the roof sheathing. There are minimum thicknesses required for this that are outlined in Building Codes.
When a home is built on a slab, it is generally built upon a layer of compacted rock, covered by a plastic shield, then a minimum of 2” rigid Styrofoam under the slab or it can use rigid foam as slab edge insulation that covers the perimeter edge of the slab and goes down to a Code required depth. Basements and crawl spaces also can be insulated below the slab and/or up the walls. The wall insulation can be either interior or exterior. If your home includes a crawl space, the rim joists should be insulated; spray foamed rim joists with plastic backed rolled insulation underneath and up the wall works well for insulation and moisture barrier. It can be extended throughout the crawl space. Depending on the climate, the floor joists may not need insulating, though it will typically be vented.
Homes built on a slab can have rigid foam under the entire slab which helps to keep the floor more comfortable Thickness of the foam is dictated by Code for the walls. Crawlspaces may be insulated with cavity insulation in the floor joists for an unconditioned crawl that is typically vented.
Any and all insulation decisions must meet the requirements of the Building Code in your area. Your builder should know what they are and your plan should meet the code.
What R-Value Should You Look For?
Generally, the higher the R-Value the better. Loye said that the IRC (International Residential Code) establishes the guidelines for construction of one- and two-family residences which includes R-value minimums. These values are different based on the Climate Zone the home is built in. Some examples from the current IRC code: wall insulation should have a minimum of R-30, with R-60 in the roof of homes constructed in zones 4-8. Floor R-values vary from R-13 in the lower zones to R-30 in the higher zones. However, states and municipalities are not required to adopt the IRC recommendations, though they usually do, often with a lag time.
Your contractor/builder should be familiar with minimum R-value requirements in the area you are building. Insulation specifications should be included in the building plan which must be approved by your municipality. While you cannot build with a lower level of insulation than code, you can choose to exceed the required R-value.
Insulation R-Values are Low! How Do You Get Them Higher?
R-Values vary from product to product. However, if you are looking at 1” of rigid foam insulation and it is labeled with an R-Value of 6.2, layer 2” and you have an R-Value of 12.4. Add a third layer and you have 18.6. If you have 6” to fill, you can get 37.2 for an R-value, though you should always leave a small air gap. The point is that when you add insulation, you add the two R-Values together.
R-Values vary for diverse types of insulation and from product to product. Insulation should be labeled for its R-Value. Some products like rigid foam and SPF are labeled per inch of thickness.
Click here to find out what R-Values are suggested by EnergyStar for residences in your area: https://www.energystar.gov/saveathome/seal_insulate/identify-problems-you-want-fix/diy-checks-inspections/insulation-r-values
